Exemplary embodiments of the present invention relate to a wind power rotor, a wind turbine, the use of a wind power rotor in a wind turbine, and to a method for converting wind energy into drive energy for the purpose of generating electrical current.
Rotors rotated by the wind and which drive a generator are typically employed to generate electrical energy using the wind. At least a portion of the wind energy is converted into electrical energy in the process. A further field of application of rotors is in wind turbines which perform work, such as pump or conveyance functions. The use of wind energy is also gaining in importance in the context of the use of renewable energy sources.
Exemplary embodiments of the present invention are directed to efficient exploitation of wind energy.
According to a first aspect of the invention, a wind power rotor has a first rotor device and a second rotor device. The first rotor device rotates about a first axis of rotation and has at least two rotor blades which move along a peripheral track around the first axis of rotation. The rotor blades are arranged in such a manner that they describe a virtual first shell surface of a virtual first rotation body about the first axis of rotation. The second rotor device rotates about a second axis of rotation and has a second rotating body with a closed second shell surface. The second rotating body is at least partially arranged inside the virtual first rotating body. The first rotor device can be driven by wind in a first direction of rotation for the purpose of converting wind energy into a drive force, and the second rotor device has a drive device and can be driven in a second direction of rotation that is opposite the first direction of rotation.
According to one exemplary embodiment of the invention, the second rotor device is constructed to achieve a deflection of a stream of air, the same caused by wind, inside the first rotor device, on the side thereof facing away from the wind, counter to the first direction of rotation.
By way of example, the deflection causes an incident flow on at least one of the rotor blades of the first rotor device, which generates an additional propulsion and therefore additional drive torque.
A Magnus effect is created by the rotation of the inner rotating body (i.e., the second rotating body), which leads to a deflection of a stream of air which is moving past. As a result of the deflection of the air, and/or a re-direction of the air stream, a rotor blade that already positioned in a region of the rotation track that faces away from the wind, as a result of an advanced rotation state, is additionally exposed to a stream of air, such that a corresponding propulsion is generated and a rotation of the first rotor device results. The deflection therefore functions such that a rotor blade positioned in the rearward region is exposed to an additional incident flow of wind, such that it is possible to generate a corresponding propulsion as a result of this additional circulation around the rotor blade, and this propulsion is available as additional drive force. In this way, the configuration provides an improved degree of efficiency.
Moreover, the deflection improves the start-up behavior of the wind power rotor. The wind power rotor according to the invention starts up at lower wind speeds compared to solutions that do not have the inner rotor (i.e., the second rotor). The deflection serves as a start-up aid, so to speak. For this reason, it is possible to exploit relatively low wind speeds at which other rotors cannot yet be operated.
According to one exemplary embodiment of the invention, the first axis of rotation is a first vertical axis of rotation, and the second axis of rotation is a second vertical axis of rotation.
According to an alternative exemplary embodiment of the invention, the first axis of rotation is a first horizontal axis of rotation, and the second axis of rotation is a second horizontal axis of rotation.
By way of example, the first axis of rotation and also the second axis of rotation can be designed as tilted and/or inclined axes of rotation relative to the horizontal and the vertical.
The terms “vertical” and “horizontal” refer to the installed position, meaning the operating position.
By way of example, the first and the second axes of rotation extend parallel to each other. The first and the second axes of rotation can also be oriented concentrically to each other, meaning that the first axis of rotation corresponds to the second axis of rotation in its position.
These embodiment variants named above apply both for vertical and for horizontal or inclined axes of rotation, which also particularly apply for the embodiments named below and also for the embodiments described in the figures.
The first and the second axes of rotation can also extend with a displacement from each other, wherein the displacement is designed in such a manner that the second rotating body is arranged during the rotation about the second axis of rotation at least partially inside the virtual first rotating body, and particularly does not touch or cross the virtual first shell surface.
By way of example, the displacement can be adjustable by means of an adjustment device, for example according to the strength of the wind or the direction of the wind.
The first axis of rotation can also extend at an incline to the second axis of rotation, wherein the inclination is designed in such a manner that the second rotating body is arranged during the rotation about the second axis of rotation at least partially inside of the virtual first rotating body, and particularly does not touch or cross the virtual first shell surface.
The inclination of the two axes of rotation can likewise be adjustable by means of an inclination adjustment device.
The rotor blades travel at least partially around the second rotating body during the rotation, meaning that at least a sub-region of the second rotating body is circled by the rotor blades.
The rotor blades each have a longitudinal extension, and extend in the direction of the first axis of rotation, wherein the term “in the direction of” refers to the fact that the longitudinal extension occurs between a first point and second point, wherein the connection line between the first and second points has a directional component running parallel to the first axis of rotation.
The rotor blades can also be characterized as repellers driven by the wind.
The rotor blades can be designed as fixed with respect to the tangential angular position thereof—meaning that they do not alter their angular position during the rotation.
By way of example, the rotor blades have a symmetric cross-section. According to a further example, the rotor blade has a symmetric wing cross-section with a first edge running to a point, and a second edge designed with a rounded shape, wherein the second edge is arranged forward in the direction of rotation.
The rotor blades can also have a wing cross-section with a curvature, however. The curvature can also be implemented by a moving flap on the front edge of the wing or the back edge of the wing.
In addition to the named variants having two rotor blades, three, four, or more rotor blades can be included. This of course also applies for the different combinations of the features described above and in the following.
The rotor blades can be divided into rotor blade segments, wherein the rotor blade segments can have different designs such that the rotor blades have a different design along the complete length thereof.
According to one exemplary embodiment, the first rotor device has a Darrieus rotor.
By way of example, the upper and lower ends of the rotor blades—for example in the case of axes of rotation running vertically—or the lateral ends—for example in the case of axes of rotation running horizontally—are arranged closer to the axis of rotation than in the region between the two ends.
According to one exemplary embodiment of the invention, the two ends of the rotor blades are arranged closer to the axis of rotation than the region thereof between the two ends, wherein the rotor blades project outward in a bow-shape.
The rotor blades can have a hyperbolic shape in the longitudinal direction; for example they can have a chain shape (hyperbolic cosine).
However, the rotor blades can also have a straight design in the longitudinal direction, and run parallel to the first axis of rotation, or be inclined with respect to the first axis of rotation.
According to one exemplary embodiment of the invention, the rotor blades run parallel to the first and to the second axis of rotation. By way of example, the rotor blades can be designed as H-Darrieus rotors.
According to a further example, the rotor blades can also be curved in a helical shape.
The second rotating body can partially project out of the virtual first rotating body in the axial direction. The second rotating body can also project out of the virtual first rotating body with its end face or both end faces thereof.
According to one exemplary embodiment of the invention, the second rotating body is arranged entirely inside the virtual first rotating body.
The second rotating body in this case is arranged inside the peripheral track of the first rotating body.
The closed second shell surface is a peripheral surface.
The second rotating body can have a circular cross-section (diameter) that remains constant around the second axis of rotation, and can form a cylinder.
The second rotating body can also have a circular diameter that varies evenly around the second axis of rotation, and can form a truncated cone.
The second rotating body can also be composed of different truncated cone segments and/or cylinder segments.
According to one exemplary embodiment of the invention, the second rotating body has different diameters along the second axis of rotation.
The circumference of the second rotating body can be matched to the virtual first shell surface; for example, it can form a defined proportion and/or a defined difference with respect to the shell surface.
The second rotating body can have a hyperbolic contour in a longitudinal cross-section along the second axis of rotation.
The second rotating body can be divided into segments that can be driven at different speeds.
The second rotating body can have an end disk projecting beyond the second shell surface, in the region of its first and/or second end. As an alternative or in addition thereto, the second rotating body can have a plurality of disks arranged between the two ends, wherein the disks have a larger diameter than one or both of the neighboring shell surface segments.
The drive device can have a coupling, for example a direct coupling of the first rotor device and the second rotor device, thereby including a reversal of the direction of rotation of the second rotor device.
By way of example, the wind power acting on the first rotor device can also drive the second rotor device.
According to a further example, a start-up aid can be included supporting the start-up of the rotor.
According to one exemplary embodiment of the invention, the drive device has a gear device between the first rotor device and the second rotor device, wherein the gear device functions to transmit the rotation speed, in addition to reversing the direction of rotation.
The transmission ratio of the gear device can be variable, for example continuously or in steps.
By way of example, the gear device can have a first ratio that is dependent on the rotation speed of the first rotor device.
By way of example, the drive device can also be disengaged by an electric motor driven by electrical current.
By way of example, the electrical current can be generated by means of the drive force, meaning that the electric motor can be driven by generator current, for example.
The electric motor can, for example, have a regulator and offer a variable transmission ratio.
The transmission in this case can be dependent on the actual inflowing wind speed and/or the strength of the wind.
The second rotating body can be driven at a circumferential speed that is approximately 0.5 to 4 times the inflowing air speed of the first rotor device.
The first rotor device can have a circumferential speed that is approximately 50% of the inflowing air speed of the wind.
The rotation ratio between the first and the second rotor devices is, by way of example, approximately 1:2 to 1:8, wherein the directions of rotation run opposite each other, as already indicated.
The ratio of the inflowing air speed of the wind power rotor/the circumferential speed of the first rotor device/the circumferential speed of the second rotating body is approx. 0.5/1/1 to 4, wherein in this case as well, the directions of rotation of the two rotor devices, as indicated above, run opposite each other. The circumferential speed in this case refers to the circumferential speed at the point of the maximum diameter.
According to one exemplary embodiment of the invention, the drive device is constructed to also drive the second rotating body in the first direction of rotation if selected.
In this case, the rotating body rotates in the same direction as the rotor blades. This can be implemented as a kind of braking effect, for example at excessively high wind speeds, because the degree of efficiency and/or the efficiency is significantly lower with rotation in the same direction—in contrast to the opposite rotation directions according to the invention of the first and the second rotating bodies, wherein the configuration leads to an improvement of the efficiency and/or to an improved exploitation of the wind energy, as illustrated above.
According to a second aspect of the invention, a wind turbine is provided that has a rotor for converting wind movement into a rotary movement, a generator for converting the energy of movement of the rotary movement into electrical energy, and a gear device for coupling the rotor to the generator to transmit the rotary movement to the generator. The rotor in this case is designed as a wind power rotor according to one of the previously described embodiments and examples/aspects.
The rotor axis can be arranged vertical or horizontal, or inclined, by way of example.
The rotor in this case can be oriented facing the direction of inflowing air.
By way of example, the wind turbine has a support structure holding the wind power rotor, the gear device, and the generator.
The support structure can be anchored in a foundation at ground level, for example, or on a structural object, such as a built structure, for example, such as a building or a bridge structure, by way of example.
A third aspect of the invention is the use of a wind power rotor according to one of the previously named embodiments, examples, and aspects, in a wind turbine.
A fourth aspect of the invention is a method for the conversion of wind energy into drive energy for the generation of electrical current, comprising the following steps:
a) rotating a first rotor device about a first axis of rotation in a first direction of rotation by means of wind power, wherein the first rotor device has at least two rotor blades that move around a peripheral track about the first axis of rotation, wherein the rotor blades are arranged in such a manner that they describe a first virtual shell surface of a virtual first rotating body upon rotation about the first axis of rotation;
b) rotating a second rotor device about a second axis of rotation in a second direction of rotation that is opposite the first direction of rotation by means of a drive device, wherein the second rotor device has a second rotating body with a closed second shell surface, and wherein the second rotating body is at least partially arranged inside the virtual first rotating body, wherein the second rotor device functions to create a deflection of an air stream caused by wind inside the first rotor device, counter to the first direction of rotation, on the side which faces away from the wind; and
c) driving a current generator by means of the first rotor device.
It is hereby noted that according to the invention, the drive energy obtained and/or converted from the wind energy can also be used for other work purposes in addition to the generation of electrical current.
One aspect of the invention is a combination of two different rotor devices, particularly a first partial rotor, so to speak, having rotor blades, in combination with a second rotating body designed as a closed body, wherein the inner, closed rotating body is exposed to the inflowing wind just like the first rotor, but only the first rotor, particularly the rotor blades, are driven by the wind itself. In contrast, the second rotor, meaning the second rotating body, is driven by the provision of a drive energy. This can be obtained from, for example, the wind power itself. The drive in this case is realized in the direction opposite that of the direction of rotation of the rotor blades, according to the invention, the same being driven by the wind. The rotation in the opposite direction creates a deflection of the air stream that flows through the wind power rotor in this case—meaning the air stream that flows through the first rotor device between the rotor blades, and/or causes the rotor blades to move in the process, by creating lift and/or propulsion (depending on the arrangement) on the rotor blades. The deflection by means of the second rotor blade creates a more favorable air stream with respect to the rotor blades, such that the wind energy is better exploited with respect to the generation of drive forces.
It is hereby noted that the features of the embodiments and aspects of the devices apply to the embodiments of the method as well as to the use of the device, and vice-versa. In addition, all features for which this is not explicitly indicated can also be freely combined with each other.